I have a directv hr21-700 hddvr with what I think is a slimline 5 dish. I have great signal strength on 99, 101, 103, 110, & 119. I get errors on 99 13V and 103 18V. I can not figure out why.this problem keeps me from getting some high definition channels If anyone could tell me that would be...

I have a HR21-700 receiver I am trying to connect to a direct phase III dish and I cannot get a signal. Is it possible they do not match? Any help is greatly appreciated.